Transient Electromagnetic Formation Estimation Using Bucking and Duhamel Integral
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Geophysical inverse problems in formation property estimation are hindered by limited data and noise, particularly electromagnetic interference from conductive tools, leading to uncertainty in model accuracy and parameter estimation.
Innovation Solution
A method and system using a single transmitter and at least two receivers in a borehole to generate and compare actual and synthetic signals, employing bucking to minimize carrier-induced noise and Duhamel's integral for approximate forward modeling, ensuring high sensitivity to formation parameters and reducing uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bucking is used to eliminate systematic noise from primary field and conductive tools, then sensitivity to formation parameters is improved, but electromagnetic interference from conductive tool body creates additional systematic noise
Solution Approach 1:
The patent measures the electromagnetic interference from the conductive tool body and uses it as a reference signal to subtract from the total measurement. By treating the harmful interference as a measurable reference, the system converts the harmful effect into a useful correction term that improves formation parameter estimation.
Solution Approach 2:
The patent separates the total measured signal into distinct components: formation response, tool body interference, and noise. By using multiple receivers and mathematical decomposition, the system isolates the formation signal from the conductive tool interference, allowing independent analysis and estimation of formation parameters.
2Loss of time
If limited data is used for inversion, then measurement time and complexity are reduced, but uncertainty in formation property estimation increases
Solution Approach 1:
The patent uses an iterative inversion process where initial formation property estimates are used to generate synthetic data, which is then compared with actual measurements. The difference (misfit) feeds back into the inversion process to refine the estimates, progressively reducing uncertainty while maintaining efficient measurement time.
Solution Approach 2:
The patent performs preliminary measurements and processing to generate initial estimates of formation properties before conducting the full inversion. This preliminary action provides a starting point that reduces the computational burden and uncertainty in the subsequent detailed analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and efficient estimation of formation properties by minimizing carrier-induced noise and improving model fits, allowing for reliable geo-steering and improved downhole operations.
Implementation Method 1
A transient electromagnetic field is generated by a transmitter... A magnetic field is produced by a transient electromagnetic field
Implementation Method 2
A magnetic field is produced by a transient electromagnetic field generated by a transmitter in the presence of air
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for estimating a property of an earth formation penetrated by a borehole, the method comprising generating a first transient electromagnetic fields with a transmitter on a carrier located outside of the borehole and receiving associated signals, calculating a bucking coefficient using the measured signals, conveying the carrier through a borehole, generating a second transient electromagnetic field and receiving associated signals, calculating, a bucked signal using the bucking coefficient and the downhole signals, calculating synthetic formation signals, calculating synthetic formations signals by applying a Duhamels integral to the measured signals and the synthetic formation signals, calculating a synthetic bucked signal, and performing an inversion of a formation model to estimate a property of the formation such that an inverted synthetic bucked signal and an inverted bucked signal coincide within a predetermined range.